The pathway of dephosphorylation of myo-inositol hexakisphosphate by phytases from wheat bran of Triticum aestivum L. cv. Nourin #61

Article abstract of DOI:10.1271/bbb.64.995

Phytases are the primary enzymes responsible for the hydrolysis of phytic acid, myo-inositol-1, 2, 3, 4, 5, 6-hexakisphosphate (InsP₆). The pathway of hydrolysis of InsP₆ by phytase from wheat bran of Triticum aestivum L. cv. Nourin #61 is proved in this study. Structures of the intermediates were established by a variety of nuclear magnetic resonance techniques (¹H-, two-dimensional ₁H-¹H coupling-correlation spectra and two-dimensional ³¹P-¹H correlation spectra), gas chromatography, and bioassay. On the basis of the structures identified, initial hydrolysis of the phosphate ester occurs at the D/L-4 position of InsP₆ to yield D/L-Ins (1, 2, 3, 5, 6) P₅. After the dephosphorylation, the pathway of dephosphorylation is divided into two routes. The main route proceeds via D/L-Ins (1, 2, 5, 6) P₄, D/L-Ins (1, 2, 6) P₃ and D/L-Ins (1, 2) P₂, while the minor route proceeds via D/L-Ins (1, 2, 3, 6) P₄, Ins (1, 2, 3) P₃ and D/L-Ins (1, 2) P₂. D/L-Ins (1, 2) P₂ is hydrolyzed at the D/L-1 or 2-position, and finally myo-inositol is produced.